Historically, plating processes were relatively slow and, therefore, were not possible in a general assembly line environment. Accordingly, parts to be plated were removed from the assembly line, transported to plating treatment locations and later retransported and replaced on the assembly line.
Recently, however, high speed plating methods have been developed. For example, Japanese Patent Publication No. 1-52,480 discloses a surface treatment device for degreasing the inside surface of the cylinder of an engine prior to chrome plating. During the process, both ends of the engine cylinder are plugged with a plug through a sealing material. One of the plugs defines a passage for the entry of treating liquid, while the other plug defines a treating liquid exit passage. Both passages are in fluid communication with the inside of the cylinder. A tank for the treating liquid, a pump, and valves are connected to a piping system for purposes of recirculating the treatment liquid from a treatment liquid reservoir through the engine cylinders and returning the treatment liquid to the reservoir. The flow of the treating liquid through the inside of the cylinder permits a higher current density to be applied to the liquid, resulting in higher plating rate.
On the other hand, this and other high speed plating devices have significant limitations. For example, in the above-described device, experience has shown that it is difficult to completely prevent the leakage of treating liquids from the inside of the cylinder. Specifically, due to the varying sizes of the walls of the crank chamber and their proximity to the cylinders being plated, it is difficult to properly seal the cylinders against leakage. Such leakage can adversely affect the quality of the plating of the cylinder, as well as result in the deposition of plating treatment liquid on the outside of the cylinder. It also poses a safety risk.
Thus, there is needed an improved surface treatment device and, in particular, an improved surface treatment device suitable for use in,plating the cylindrical walls of engine blocks.